From: Liu Shixin Date: Fri, 29 Apr 2022 21:38:04 +0000 (-0700) Subject: fs: sysv: check sbi->s_firstdatazone in complete_read_super X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f6e2c20ca7604e6a267c93a511d19dda72573be1;p=linux.git fs: sysv: check sbi->s_firstdatazone in complete_read_super sbi->s_firstinodezone is initialized to 2 and sbi->s_firstdatazone is read from sbd. There's no guarantee that sbi->s_firstdatazone must bigger than sbi->s_firstinodezone. If sbi->s_firstdatazone less than 2, the filesystem can still be mounted unexpetly. At this point, sbi->s_ninodes flip to very large value and this filesystem is broken. We can observe this by executing 'df' command. When we execute, we will get an error message: "sysv_count_free_inodes: unable to read inode table" Link: https://lkml.kernel.org/r/20220330104215.530223-1-liushixin2@huawei.com Signed-off-by: Liu Shixin Reviewed-by: Christoph Hellwig Signed-off-by: Andrew Morton --- diff --git a/fs/sysv/super.c b/fs/sysv/super.c index d1def0771a408..3365a30dc1e0c 100644 --- a/fs/sysv/super.c +++ b/fs/sysv/super.c @@ -312,7 +312,9 @@ static int complete_read_super(struct super_block *sb, int silent, int size) sbi->s_firstinodezone = 2; flavour_setup[sbi->s_type](sbi, &sb->s_max_links); - + if (sbi->s_firstdatazone < sbi->s_firstinodezone) + return 0; + sbi->s_ndatazones = sbi->s_nzones - sbi->s_firstdatazone; sbi->s_inodes_per_block = bsize >> 6; sbi->s_inodes_per_block_1 = (bsize >> 6)-1;